NEW YORK — A revival of the Burton Lane musical “Finian’s Rainbow” will not find its pot of gold at the Ahmanson Theater in Los Angeles this summer after all.Producer Robert Hess ran into financial problems with the L.A. presentation, which anticipated a possible opening on Broadway this fall. The Ahmanson is now 0 for 2 in its July-August slot: A pre-Broadway run of the new musical “The Night They Raided Minsky’s” had been previously announced for a summer engagement at the theater, but had to be postponed when its director, Mike Ockrent, died last year. “Finian’s Rainbow” opened on Broadway in 1947. The Hess revival played Miami and Cleveland last fall, using a retooled book by Peter Stone, who adapted the story from the original by E.Y. Harburg and Fred Saidy.